David Cameron claims the Conservatives 'stand for society' in his party's manifesto. Photograph: Mark Large/AP

This was the moment when David Cameron showed he meant it. What that "it" is and whether it will work is a much less certain experiment, but today's manifesto launch was a brave one-way leap.

He could have retreated in the face of narrowing polls to a focus-group manifesto, a heap of rude comments about Gordon Brown and some subtle hints about stern school discipline and low taxes. It is what the party did in 2005, and Cameron should know because he wrote it. Lots of Tories are urging Cameron to dump his happy talk, the Fotherington-Thomas optimism. There wasn't anything here for the Daily Mail or the Telegraph. Taking questions, Cameron didn't even bother to call journalists from these two Tory papers. But he did call the Guardian and the Financial Times.

Today the hoody-hugging Cameron of 2006 trumped the austerity leader of 2009: vote blue, go green is back. He has risked fighting this election on an idea: that the state is the obstacle not the originator of the good society. In the end, your response to the election will boil down to whether you agree with this claim (and feel the Tories mean it) or whether, as Labour argued perfectly reasonably yesterday, this is a moment for government. Is Britain centre-right or social democratic by instinct?

Cameron's best moment was a powerful riff on what is wrong with politics: "Politicians have been treating people like mugs for 40 years," he said. "Glad that's off my chest." It sounded real, which Cameron doesn't always. "It's how we talk in private," one close friend of his said afterwards.

It's reasonable, of course, to ask whether the Tory big society isn't, underneath, standard-issue, small-state conservatism viewed down the wrong end of the telescope. Which bit does Cameron want more: less government, or more social action? By praising the latter, he hides the former.

And even if Cameron's audacious claim – "we stand for society" – is true (and I think it might be), his vision is of the boy-scout society, everyone dutifully doing their good deed for the day. It is the sort of world in which Ambridge's Lynda Snell might flourish, but that doesn't mean it will work for the poor.

So there are plenty of reasons to doubt. But there was a coherence to Cameron today which even sceptics should note. Just as, in 1997, the Conservatives made a mistake in thinking the Labour party was still the unchanged party of 1983, so I think Labour shouldn't mistake Cameron's party for the same old Tories. Yes, the remoulding is imperfect. True, many Conservatives don't believe in it. But something is going on here.